The Florida peninsula inland scrub is a shrubland community found on the Florida peninsula. The largest remaining blocks of inland scrub are in and around the Ocala National Forest and in the Lake Wales Ridge National Wildlife Refuge. The Archbold Biological Station near Lake Placid contains about 20 km2 (7.7 sq mi) of scrub habitat and sponsors biological research on it. The scrub occurs on a series of north-south running ridges composed of sand derived from ancient dune fields. The soil, a type of entisol, is derived from quartz and is low in organic matter, silt, and clay. Because the low-nutrient sandy soils do not retain moisture, the ecosystem is effectively an arid one.